The unveiling of the new-season fashion campaigns always causes a ripple of excitement, but what's got us most interested isn't Lady Gaga done up as Donatella for Versace's spring summer ads or how Daria Werbowy found the time to star in all her campaigns, but a new face: 26-year-old fashion blogger Jillian Mercado.

Mercado stars in the new campaign for Diesel, alongside the artist James Astronaut, shot by the influential fashion photographers Inez van Lamsweerde and Vinoodh Matadin. Fashion bloggers have long been considered the new "stars" of the industry, so it's no real surprise there – and Mercado is certainly stylish and has an extraordinary face – but she isn't exactly your traditional model: she was diagnosed with spastic muscular dystrophy as a child, and has used a wheelchair since she was 12.

Mercado, who writes the blog Manufactured 1987 and is executive editorial director of We the Urban digital magazine, knew Diesel's artistic director Nicola Formichetti through work. Still, she didn't expect to get anywhere when she (along with some of her friends) entered themselves for Diesel's open casting call in the summer. "I didn't put much hope in it. It was just something I did for fun."

She is clearly thrilled. "It means so much to me because it's the fact that someone who is different is representing Diesel," she says. "[It shows] anyone can rock the clothes and look beautiful. For me it represents way more than just a campaign. A lot of people will see it and will have a change of mind of how they see people who have a disability."

Mercado chose to go into an industry not exactly known for its inclusivity or broad ideas about what constitutes "beautiful". But she grew up, born and raised in New York, with an interest in fashion – her mother was a seamstress, her father worked in a shoe store – and she went on to study at the Fashion Institute of Technology. "I knew how narrow minded the fashion industry could be," she says, but she didn't see why that should stop her. "If you want to do something, it takes dedication but it doesn't matter what other people say. Be you and go for it – I try to keep that in mind." But she found, she says, that "the industry has always welcomed me. I'm always aware of negative looks or things people say but I've been welcomed and people respect me for who I am. The industry is moving forward."

There has been a small push in recent years to get the fashion industry to embrace a wider range of beauty – the organisation Models of Diversity is one group which campaigns for this, All Walks Beyond the Catwalk is another. But representations of disability are all but invisible once you reach the top tiers of the fashion industry (the athlete and actor Aimee Mullins, who starred in Alexander McQueen's catwalk show in 1998 and has been a L'Oreal ambassador, appears to be the lone exception).

"I hope something does happen, or continues to happen, like this [campaign]," says Mercado. "People should have an open mind. If I'm helping to make it move forward, that's awesome."